Sealing closure for electric batteries

ABSTRACT

Sealing closure for electric batteries includes, in the bottom of the anode, a metal tray provided on the periphery of its base with a zig-zag cross-sectional profile and in its central zone with a projection to the outside, which is covered internally by a film of anti-corrosive product. The outer zone of the tray surrounding the central projection is provided with a thermoplastic material, leaving free the aforesaid outer central projection of the base of the tray.

July 9, 1974 u. LOPEZ SANCHEZ SEALING CLOSURE FOR ELECTRIC BATTERIESP1106 July 5. 1972 FIG. 1

FIG. 3

United States Patent 3,823,039 SEALING CLOSURE FOR ELECTRIC BATTERIESDemetrio Lopez Sanchez, Madrid, Spain, assiguor to Pilas Secas Jupiter,S.A., Tolosa, Guipuzcoa, Spain Filed July 5, 1972, Ser. No. 269,088Claims priority, applicastign Spain, Dec. 24, 1971,

Int. Cl. nolm 1/02 U.S. Cl. 136-133 4 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND OF THE INVENTION The present invention relates to a type ofsealed closure for electric batteries, which enables them to be keptfree from leaks of corrosive liquid from the commencement of their useuntil they are exhausted.

There have been tested and put into practice various types of electricbatteries which comply with the proposed aim regarding tightness, suchas represented by Spanish Utility Models Nos. 125,958; 125,959; 125,960;125,961; 126,121; 126,122; 126,569; 126,570, and 171,501.

However, the present inventor has conceived a sealed closure which issimpler to produce and gives better results, and which is the object ofthe present invention.

As is known, a battery forms water during its discharge at the same timeas its electrolytic paste or electrolytic bridge between anode andcathode retrogresses. As a result of the combination of these twoeffects the pressure inside the closed container constituting thebattery is raised, and this is further enhanced by the increase of heatproduced by the chemical reactions taking place. This has the effectthat because of its higher pressure in relation to atmospheric pressurethe liquid tends to escape at moments when its formation is greatest,and it is consequently necessary that the battery should at all timeswithstand this combined internal pressure of the gas and the liquid,since subsequently the liquid formed will react chemically with solidproducts, forming chemically complex substances and to a large extentre-absorbing the original liquid.

*SUMMARY OF THE INVENTION The device according to the present inventionis essentially characterized in that the zinc tube or anode of thebattery has a negative current collector tray having a base with anupwardly extending lip peripherally fastened to the bottom thereof inorder to make electric contact. The base of the tray has a zig-zagcross-section formed by a downwardly and outwardly extending annularprojection formed of a first annular flange extending downwardly andoutwardly at an acute angle to the horizontal and a second annularflange extending inwardly and upwardly from the lower extremity of thefirst annular flange at an acute angle to the first annular flange andthe horizontal. Extending downwardly from the upper extremity of thesecond annular flange, and preferably at a right angle thereto, is acentral projection or dished portion extending to the outside andconstituting the contact zone of the negative pole, for the utilizationof the battery.

3,823,039 Patented July 9, 1974 ice This special form of the tray hasthe effect that when thermoplastic material is injected around theannular projection, once the outer casing has been fitted, the materialcontracts against the annular projection of the metallic tray and iswelded to the outer tubular casing of heat-sealable material whichsurrounds the entire battery, thereby ensuring a perfect seal at thebase of the electric batteries through the intimate bonding between theouter casing and the material forming a thickened base, and also throughthe contraction force of the thermoplastic material injected against theannular projection of the tray. The annular projection at an acute angleto the tray anchored in the thermoplastic material constitutes acircular closure or sealing zone because it is under a higher pressurethan the pressure formed internally during discharge. At moments ofmaximum formation of gas and liquid the tubular base tends to swellslightly, its edges acting on the thickened zone being contracted andapplying additional closing pressure to the annular acute-angleprojection of the tray.

BRIEF DESCRIPTION OF THE DRAWINGS To facilitate the understanding of theinvention reference will be made to the following description taken withthe accompanying drawings showing one illustrative example, which doesnot constitute a limitation, and wherein: FIGS. 1 and 2 show two viewsof the tray, in plan and in profile, respectively; FIG. 3 is a sectionalelevation of the hermetic sealing of the bottom of the battery employingthe tray of FIGS. 1 and 2; and FIG. 4 shows in detail the contractionzone of the heat-sealable material injected into the acute angle of thetray.

DETAILED DESCRIPTION OF THE INVENTION The various elements have beengiven the following numerical references in the four figures of thedrawings:

1. Metal tray (negative pole or cathode device of the battery).

2. Acute angle of the annular projection of the tray.

3. Right angle of the dished portion of the tray.

4. Outer tubular casing possessing heat-sealing properties.

5. Zinc tube (container and anode of the battery).

6. Thickened zone of the outer base of the battery.

7. Central projection or dished portion of the tray which projectsdownwardly and outwardly of the cover and constituting the contact zoneof the negative pole, for the utilisation of the battery.

8. Welding zone between casing and injected material.

9. Chamber formed between the central projection 7 and the base of zinctube 5.

10. Anti-corrosive film covering the inside of the base of the metaltray 1.

The metal tray 1 has a base with a zig-zag cross-section formed by adownwardly and outwardly extending annular projection formed therein.The annular projection consists of a first annular flange 1a extendingdownwardly and outwardly at an acute angle 2 from the horizontal, and asecond annular flange 1b extending inwardly and upwardly from the lowerextremity of the first annular flange at an acute angle to the firstannular flange and the horizontal. A central projection or dish-shapedportion 7 extends downwardly from the upper extremity of the secondannular flange. Also an annular lip 10 extends upwardly from theperiphery of the base to contact the outer periphery of the bottomportion of zinc tube 5. Thermoplastic material is injected against theannular projection once the tray has been fitted on the bottom of theanode 5 and the outer tubular casing 4 has been fitted thereover.Because of the temperature of the injected material the tubular casing 4melts at the Zone 8 in contact with the material, so that the two areintimately welded together by fusion. In addition, because of thecontraction occurring after cooling following the injection the injectedmaterial in the zone 6, contraction of the material in the angles 2 and3 exerts pressure against the metal tray, so that the battery ishermetically sealed through this pressure on the annular projection. Inthis manner the liquid and gas formed in the battery are held captivebetween the metal tray and the thickened zone 6, the latter being shownparticularly clearly in FIG. 4, where the directions of the sealingforce have been shown by arrows. The contraction force is assisted bythe force produced by the swelling of the casing, and the two forcesresult in tight sealing against the annular projection.

In addition, the chamber 9 formed between the central projection 7 ofthe tray and the base of the tube will serve to permit expansion of thegases and liquid produced in the interior of the battery. In order toprevent the corrosion of the inside of the base of the metal traythrough the action of this corrosion liquid, the aforesaid inner side ofthe base may be provided with a fine film 10 of anticorrosive product.

The above are the essential characteristics of the invention, the scopeof protection of which includes all those modifications of details whichdo not change, alter, or modify the essential nature of the invention.

I claim:

1. In a base for electric sealed batteries including a tubular anode, asealing cover surrounding said anode, and a cathode device in contactwith said anode and extending outwardly through said cover; theimprovement wherein:

said cathode device comprises:

a metal tray having a base, said base having a zigzag cross-sectionalprofile formed by a downwardly and outwardly extending annularprojection formed of a first annular flange extending downwardly andoutwardly at an acute angle from the horizontal, and a second annularflange extending inwardly and upwardly from the lower extremity of saidfirst annular flange at an acute angle to said first annular flange andto the horizontal;

an annular dish-shaped central projection extending downwardly from theupper extremity of said second annular flange;

an annular lip extending upwardly from the outer periphery of said base,said lip being in contact with said tubular anode about the periphery ofthe bottom portion thereof; and

there being an expansion chamber formed by said central projectionbetween said tray and the bottom of said anode.

2. The improvement claimed in claim 1, wherein said central projectionextends downwardly at a substantially right angle to said second annularflange.

3. The improvement claimed in claim 1, further comprising thermoplasticmaterial means inserted between said sealing cover and the bottomsurface of said base of said tray for exerting a contracting pressure onsaid annular projection.

4. The improvement claimed in claim 3, wherein said thermoplasticmaterial means forms a unitary body rigidly welded to the interior ofsaid sealing cover.

References Cited UNITED STATES PATENTS 3,573,990 4/1971 Tsuchida et al.136133 3,185,594 5/1965 Urry 136-107 2,996,565 8/1961 Ning 136-1323,433,681 3/1969 Iammet 136-133 3,457,117 7/1969 Angelovich 136-433ANTHONY SKAPARS, Primary Examiner US. Cl. X.R. 136-469

